1. Field of the Invention
The present invention relates to an image recording apparatus which directly controls a flow of charged toner particles by a toner particle control electrode and records an image on an image recording medium.
2. Description of Related Art
Image recording apparatus which directly control the flow of toner particles when recording an image on an image recording medium are known. One such image recording apparatus is disclosed in U.S. Pat. No. 3,689,935. The construction and the operation of this kind of image recording apparatus are briefly explained as follows.
The image recording apparatus comprises a toner particle supply portion, a toner particle control member, and a back electrode. The toner particle supply portion supplies the charged toner particles below the toner particle control member. The toner particle control member has a plurality of apertures through which the charged toner particles which are supplied from the toner particle supply portion can pass and selectively controls the passage of the toner particles.
The back electrode confronts with the toner particle supply portion through the toner particle control member, and there is a space between the back electrode and the toner particle control member where the image recording medium on which the image will be formed can pass. When the image recording medium passes through the space, the toner particle control member selectively allows the passage of the toner particles through the aperture. The back electrode attracts the toner particles which have passed the aperture of the toner particle control member to the image recording medium on which the image is formed.
The charged toner particles are supplied from the toner particle supply portion to the lower side of the toner particle control member, and a flow of the toner particles is controlled by an electric field in each aperture. The controlled toner particles are attracted in the direction of the back electrode through the aperture, are adhered to the image recording medium which is fed along the back electrode, and the image is formed thereon. A high voltage of about 1 kV (kilovolt) is applied to the back electrode, and the space between the toner particle control member and the back electrode is about 1 millimeter.
However, the image cannot be recorded on a thick image recording medium with this image recording apparatus. That is, the space between the toner particle control member and the back electrode is about 1 millimeter, as mentioned above, so that the image is recorded on the image recording medium when it can pass such a space. But if the image recording medium is thicker than 1 millimeter, it cannot pass through this space and the image cannot be recorded on such an image recording medium.